Add phpdoc ColumnSchema. (#254)

src/ColumnSchema.php

@@ -13,20 +13,40 @@
 use function json_decode;
 
 /**
- * The class ColumnSchema for Mysql database.
+ * Represents the metadata of a column in a database table for Mysql, MariaDb Server. It provides information about the
+ * column's name, type, size, precision, and other details.
+ *
+ * Is used to store and retrieve metadata about a column in a database table. It is typically used in conjunction with
+ * the TableSchema class, which represents the metadata of a database table as a whole.
+ *
+ * Here is an example of how the ColumnSchema class might be used:
+ *
+ * ```php
+ * use Yiisoft\Db\Mysql\ColumnSchema;
+ *
+ * $column = new ColumnSchema();
+ * $column->name('id');
+ * $column->allowNull(false);
+ * $column->dbType('int(11)');
+ * $column->phpType('integer');
+ * $column->type('integer');
+ * $column->defaultValue(0);
+ * $column->autoIncrement(true);
+ * $column->primaryKey(true);
+ * ```
  */
 final class ColumnSchema extends AbstractColumnSchema
 {
     /**
      * Converts the input value according to {@see phpType} after retrieval from the database.
      *
-     * If the value is null or an {@see Expression}, it will not be converted.
+     * If the value is `null` or an {@see \Yiisoft\Db\Expression\Expression}, it will not be converted.
      *
-     * @param mixed $value input value.
+     * @param mixed $value The value to be converted.
      *
-     * @throws JsonException
+     * @throws JsonException If the value cannot be decoded.
      *
-     * @return mixed converted value.
+     * @return mixed The converted value.
      */
     public function phpTypecast(mixed $value): mixed
     {
@@ -44,12 +64,12 @@ public function phpTypecast(mixed $value): mixed
     /**
      * Converts the input value according to {@see type} and {@see dbType} for use in a db query.
      *
-     * If the value is null or an {@see Expression}, it will not be converted.
+     * If the value is `null` or an {@see \Yiisoft\Db\Expression\Expression}, it will not be converted.
      *
-     * @param mixed $value input value.
+     * @param mixed $value The value to be converted.
      *
-     * @return mixed converted value. This may also be an array containing the value as the first element and the PDO
-     * type as the second element.
+     * @return mixed The converted value. This may also be an array containing the value as the first element and the
+     * PDO type as the second element.
      */
     public function dbTypecast(mixed $value): mixed
     {